Problems with Eg4 6500ex buyer beware.

[timselectric]

Sounds good. I guess I still don't understand what the firmware upgrade has to do with it though...

It just keeps the relay engaged in all modes.
(Neutral pass through)

 

[Samsonite801]

It just keeps the relay engaged in all modes.
(Neutral pass through)

Oh ok, so does that mean they just leave the N-G bond screws in the units from factory, since they adjust it in firmware and keep it open via the relays?

 

[timselectric]

Oh ok, so does that mean they just leave the N-G bond screws in the units from factory, since they adjust it in firmware and keep it open via the relays?

The screws are removed at the factory.
I assume it's because the relay could fail.
I'm not a fan of using the relay for this setup.
I prefer to add a permanent connection (jumper) between the input neutral and output neutral terminals.

 

[Zwy]

This is a common neutral setup.
Neutral pass through/ bonding relay should remain in neutral pass through mode.
The only N/G bond should be provided by your existing service. In all modes.

In theory it sounds good.

However in practice it may not be ideal. There is resistance/impedance in the neutral and ground circuits that increases as the length of the circuit increases. Voltage potential at one end of the wire is different than the other end. Each connection adds more resistance.

Don't get me wrong, I agree a N/G bond at one location is ideal. The inverters are source and usually mounted far away from N-G bond location in a rural setting. That resistance/impedance causes some problems.

 

[Zwy]

Yeah if you have grid input, then you rely on the neutral/ground bond which should already exist in or near your MSP. If you don’t have any grid input, the recommendation is to make a ground/neutral bond in your critical loads panel (or your first panel downstream of the inverter).

If neutral is switched, N-G bond is needed at the inverter.

With the LV6548, the internal transfer switch will switch input neutral. It is not a common neutral setup like the 6500EX with later firmware. A N-G bond at the inverter is needed for ground fault protection. The 6500EX on the other hand is not switching neutral but instead it considered pass thru with the firmware updates. It relies on the N-G bond at the service disconnect.

I never updated the firmware in the LV6548, they work great right out of the box.

 

[Zwy]

Oh ok, so does that mean they just leave the N-G bond screws in the units from factory, since they adjust it in firmware and keep it open via the relays?

Some units have the screw, some don't. Later manufacture dates as a rule don't have the screw, however on still needs to check.

The 6500EX bonding relay is closed when not powered. There is the possibility of the relay failing closed, thus leading to a N-G bond in 2 locations as the 6500EX relies on the pass thru neutral and N-G bond at the service disconnect.

 

[Zwy]

I suspect this is what's happening right now with no NG bond at the loads panel inside. He's measuring 7 volts N to G at loads panel unbonded.

That video was from the first pair of 6500EX's. The 7V is present when the lights strobe and inverter output voltage fluctuates between 112V to 128V. , I believe it is peak to peak voltage and is inductive due to the inverter output voltage fluctuations. I captured it with the scope also. When lights are not strobing, the voltage is under 3V.

In this video, I had stairs lights strobing and recorded the 7V between N and G. As soon as the load increased by switching on the lights, the voltage dropped to noise. You have to watch the full video to see when the lights are turned on.

This could mean that there is current on the ground wire going out to the NG bond at the pole and returns via N wire. Could be due to miswired appliance where N is wired to G putting return current onto the ground wire. His LV6548 that did not exibit this problem did have NG screw in one of the units which would be enough to NG bond both inverters via inverter case ground.

What is occurring from my point of view is current is trying to return to source on the neutral, but for some reason, the inverter voltage on neutral is high. The current is still trying to return and it goes thru the neutral to the N-G bond and is returning back to the inverter on G. This is why the inverter displays the fluctuating output voltage as the zero voltage reference (Ground) is fluctuating also. I've done quite a bit of research and feel this is what is occurring.

In my case, the voltage is higher because of the impedance on the N-G bond circuit due to the distance to the service disconnect. My theory is when another load is placed on the inverter, it creates a current change and the inverter can adjust output voltage to stabilize.

If N-G bond is close to the inverter and there is little impedance (large wires), then most likely the "problem" wouldn't be noticed.

 

[timselectric]

In theory it sounds good.

However in practice it may not be ideal. There is resistance/impedance in the neutral and ground circuits that increases as the length of the circuit increases. Voltage potential at one end of the wire is different than the other end. Each connection adds more resistance.

Don't get me wrong, I agree a N/G bond at one location is ideal. The inverters are source and usually mounted far away from N-G bond location in a rural setting. That resistance/impedance causes some problems.

If everything is wired correctly. And the equipment works correctly. The resistance of the N/G bond has no bearing on the system. Until there is a fault condition. So as long as the resistance doesn't impede the ability to clear the fault. The distance or location doesn't matter. It takes a lot of resistance to stop a dead short from clearing a fault.

 

[bones1]

This is an excellent thread. What is causing the flickering and voltage fluctuation if not the G/N debacle? And how is it corrected?

 

[timselectric]

This is an excellent thread. What is causing the flickering and voltage fluctuation if not the G/N debacle? And how is it corrected?

Could be a not perfect sine wave. Or poor quality led driver or dimmer.

 

[Samsonite801]

Could be a not perfect sine wave. Or poor quality led driver or dimmer.

Has anyone tried putting on a center-tap auto-transformer in parallel on the inverter outputs to see if it can help with the flickering? I know you shouldn't have to because it should just work, but I wonder if it could help...

 

[timselectric]

It wouldn't help in my opinion.
It wouldn't change the sine wave. Or the quality of the led products.
Transformers can help with surges. But that's not the issue with the flickering in this case.

 

[Samsonite801]

It wouldn't help in my opinion.
It wouldn't change the sine wave. Or the quality of the led products.
Transformers can help with surges. But that's not the issue with the flickering in this case.

I just wonder if an auto-transformer could help to better balance the neutrals from both inverters across the hot legs.. I'd be curious to see someone try one just to rule out if it can help stabilize the sine waves to each other...

I wonder if the flickering has any correlation to whether the loads are more imbalanced or balanced between the two inverters during the time when the flickering is occurring..

If each inverter is running at different loads levels say, then the neutrals might have slightly or moderately different things (current or voltage fluctuations) going on with the sine waves, and where they are bridged together, because both inverters are fighting on the same neutral.

I'd almost like to see someone hook up a 2-channel scope one on each inverter and see how the 2 waves play with each other during flickering... (or even 3 simultaneous channels for 240v, 120v, 120v)

Maybe I'm trying to overthink it, but I would still want to try it just because I'd be curious how it could possibly change the wave with an auto-transformer.

 

[timselectric]

I just wonder if an auto-transformer could help to better balance the neutrals from both inverters across the hot legs.. I'd be curious to see someone try one just to rule out if it can help stabilize the sine waves to each other...

There's only one sine wave.
Transformers don't change the wave. They change the voltage.
They can balance the system. But not in parallel with the neutral. They should create the neutral. Input 240v from the inverters. And create the split-phase.
Then the two inverters will always be perfectly balanced.

Edit: if using a grid input. It would have to be an isolation transformer. Not an autotransformer.

 

[Samsonite801]

There's only one sine wave.
Transformers don't change the wave. They change the voltage.
They can balance the system. But not in parallel with the neutral. They should create the neutral. Input 240v from the inverters. And create the split-phase.
Then the two inverters will always be perfectly balanced.

Edit: if using a grid input. It would have to be an isolation transformer. Not an autotransformer.

There's 3 perspectives on the sine wave (each of those conductors can influence, like push or pull on the same wave having an overall effect on it)... Theoretically they should all agree. I might be curious even to unbridge the neutral between the inverters for a test and see if they still agree.

 

[Samsonite801]

There's only one sine wave.
Transformers don't change the wave. They change the voltage.
They can balance the system. But not in parallel with the neutral. They should create the neutral. Input 240v from the inverters. And create the split-phase.
Then the two inverters will always be perfectly balanced.

Edit: if using a grid input. It would have to be an isolation transformer. Not an autotransformer.

Transformers build up magnetic flux in the core and saturate, they can help act like a 'flywheel' (supposedly), like a energy storage, and could potentially help smooth out voltage or current fluctuations (also known to help balance loads between legs), which could help with the load sensing circuit in the inverters to see smoother value which could help them to maintain a smoother output sine wave.

Just my general theory, you are right that they don't alter the sine wave directly. Thus my theory that a center-tap auto-transformer, wired in parallel to the output circuit could help smooth out some harmonics caused by voltage and current fluctuations that could be possibly causing the inverters to react negatively via load adjustments where it is trying to maintain consistent sine wave. (I hope I'm articulating it in a decent fashion)

I'm no engineer either, just thinking it's possible, no concrete science I have to remember or reference my gut-based theory here, disclaimer, I am just some DIY wannabe hobbyist (with a little troubleshooting experience under my belt)..

 

[timselectric]

Transformers build up magnetic flux in the core and saturate, they can help act like a 'flywheel' (supposedly), like a energy storage, and could potentially help smooth out voltage or current fluctuations (also known to help balance loads between legs), which could help with the load sensing circuit in the inverters to see smoother value to help keep a smoother output sine wave.

Just my general theory, you are right that they don't alter the sine wave directly. Thus my theory that a center-tap auto-transformer, wired in parallel to the output circuit could help smooth out some harmonics caused by voltage and current fluctuations that could be possibly causing the inverters to react negatively via load adjustments where it is trying to maintain consistent sine wave. (I hope I'm articulating it in a decent fashion)

I'm no engineer either, just thinking it's possible, no concrete science I have to remember or reference my gut-based theory here, disclaimer, I am just some DIY wannabe hobbyist (with a little troubleshooting experience under my belt)..

I don't believe that it would help in this situation.
But, it wouldn't hurt anything. If someone wanted to test it. I would test it if I could. Just because I like to verify theories.
I have plenty of transformers lying around. But I don't have any of these units.
Maybe someone else will try it, and let us know.

 

[Quattrohead]

I think zwy has a somewhat unique situation where his ground neutral bond was a very long distance away from the inverter and the impedance and capacitance of the feed has ended up freaking the inverter out. A more local neutral ground bond instead should resolve some of this issue but it still seems like some of these inverters are very delicate.

 

[SparkyJJO]

Why is the inverter so far away from the N-G bond? I don't understand his setup.

 

[timselectric]

I think zwy has a somewhat unique situation where his ground neutral bond was a very long distance away from the inverter and the impedance and capacitance of the feed has ended up freaking the inverter out. A more local neutral ground bond instead should resolve some of this issue but it still seems like some of these inverters are very delicate.

These inverters can operate in a bonded or floating system. The N/G bond should have no affect on the inverters. (As long as everything is wired correctly)

 

[Zwy]

If everything is wired correctly. And the equipment works correctly. The resistance of the N/G bond has no bearing on the system. Until there is a fault condition. So as long as the resistance doesn't impede the ability to clear the fault. The distance or location doesn't matter. It takes a lot of resistance to stop a dead short from clearing a fault.

It will clear a fault, that isn't the issue.

The problem is the inverter is using G as a zero voltage reference point. From what I have seen, the inverter neutral voltage is erratic and this creates the problem. Why? I don't know but it has to do with the internal circuitry and voltage sensing.

This is an excellent thread. What is causing the flickering and voltage fluctuation if not the G/N debacle? And how is it corrected?

The voltage fluctuation is caused by the inverter and it goes into a feedback loop. It's possible there is induction causing the feedback loop.

Could be a not perfect sine wave. Or poor quality led driver or dimmer.

Sine wave (can look great) moves up and down which is voltage peak to peak fluctuating. This video shows this occurring, the lights were flickering and inverter shows the output voltage changing (near end of video). Sorry about the upside down scope part.

This is a voltage regulation problem, I've stated it to James several times. I think they looked into it, can't find a solution and so the problem will never get fixed.

 

[Zwy]

Why is the inverter so far away from the N-G bond? I don't understand his setup.

I have an acreage and have 4 buildings on it. Meter socket is at the utility pole and that is where the main disconnect is located with a main service panel. Each building has a feeder from the main service panel. House is 90 feet from pole, shop is 120 feet, cold storage is 80 feet behind the shop and another small storage shed is 5 feet from the main service panel.

This is how all acreages and farms are wired in this area. It is a good setup, the N-G bond is located close to the utility transformer which would be source. When you add another source, it changes things if it is not close to the N-G bond.

 

[Zwy]

Has anyone tried putting on a center-tap auto-transformer in parallel on the inverter outputs to see if it can help with the flickering? I know you shouldn't have to because it should just work, but I wonder if it could help...

I looked into whether an isolation transformer might help and it would but adds more complexity. Commonly done in industrial settings where bonding close to the source would be beneficial.

 

[AntronX]

The problem is the inverter is using G as a zero voltage reference point.

You can test that by disconnecting AC output of inverter from the panel and by connecting some load like 60w incandescent light bulb between hot and ground (or neutral and ground if inverter is really incorrectly wired).

 

[SparkyJJO]

I have an acreage and have 4 buildings on it. Meter socket is at the utility pole and that is where the main disconnect is located with a main service panel. Each building has a feeder from the main service panel. House is 90 feet from pole, shop is 120 feet, cold storage is 80 feet behind the shop and another small storage shed is 5 feet from the main service panel.

This is how all acreages and farms are wired in this area. It is a good setup, the N-G bond is located close to the utility transformer which would be source. When you add another source, it changes things if it is not close to the N-G bond.

Oh ok, that makes sense.